前言

Damn Vulnerable Web Application (DVWA) 是一个包含多种 Web 应用程序漏洞的应用程序,每种漏洞包含 4 个级别的攻击难度。

PS:虽然但是应该用稳定的 1.9 版本来着x

实验环境

  • VirtualBox 6.0.18
  • Ubuntu 16.04.6 Server
  • DVWA v1.10 *Development*
  • PHP 7.0
  • Apache 2.4.18
  • Mysql 5.7.28

项目地址

Brute Force

暴力破解

Low

源码解析

直接用 $_GET 从 URL 中获取参数,未对用户名和密码进行检查和过滤。并使用未经处理的值进行数据库查询。

显然这里可以暴力破解,还可以进行 SQL 注入。

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<?php

if( isset( $_GET[ 'Login' ] ) ) {
// Get username
$user = $_GET[ 'username' ];

// Get password
$pass = $_GET[ 'password' ];
$pass = md5( $pass );

// Check the database
$query = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";
$result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' );

if( $result && mysqli_num_rows( $result ) == 1 ) {
// Get users details
$row = mysqli_fetch_assoc( $result );
$avatar = $row["avatar"];

// Login successful
echo "<p>Welcome to the password protected area {$user}</p>";
echo "<img src=\"{$avatar}\" />";
}
else {
// Login failed
echo "<pre><br />Username and/or password incorrect.</pre>";
}

((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);
}

?>

漏洞利用

Burp Suite

首先配置浏览器使用 Burp Suite 代理,利用 Burp Suite 中的 Proxy 模块拦截数据包,从拦截到的请求数据看来用户名和密码都是明文传输。

将请求数据发送到 Intruder 模块进行暴力破解,爆破字典使用 Kali 内置的字典 /usr/share/wordlists/fasttrack.txt,共 222 项。

使用 § 符号标记需要测试的数据,使用常用的默认管理用户名 admin 进行爆破测试~~(偷懒)~~。

根据返回的数据长度推测爆破成功,即密码为 password

手工 SQL 注入

根据源码分析存在注入漏洞,以下为注入语句

  • admin'#
  • admin'--
    • MySQL 注释 #-- (空格)
  • admin' or' 1'='1
    • 利用布尔值

参阅

Medium

源码解析

对用户名和密码进行处理,使用函数 mysqli_real_escape_string 转义 SQL 语句中使用的字符串中的特殊字符;增加了延迟机制,登陆失败时使用函数 sleep 延迟 2 秒。

这种情况仍然可以直接暴力破解,只是爆破的时间会有所增加。

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<?php

if( isset( $_GET[ 'Login' ] ) ) {
// Sanitise username input
$user = $_GET[ 'username' ];
$user = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $user ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));

// Sanitise password input
$pass = $_GET[ 'password' ];
$pass = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $pass ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));
$pass = md5( $pass );

// Check the database
$query = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";
$result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' );

if( $result && mysqli_num_rows( $result ) == 1 ) {
// Get users details
$row = mysqli_fetch_assoc( $result );
$avatar = $row["avatar"];

// Login successful
echo "<p>Welcome to the password protected area {$user}</p>";
echo "<img src=\"{$avatar}\" />";
}
else {
// Login failed
sleep( 2 );
echo "<pre><br />Username and/or password incorrect.</pre>";
}

((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);
}

?>

漏洞利用

和 Low 级别相同的方法,使用 Burp Suite 仍然可以暴力破解。

参阅

High

源码解析

使用 Anti-CSRF Token 来避免 CSRF 攻击,登陆时先对 token 进行检查,然后使用 stripslashes 对用户名和密码进行转义,最后进行数据库查询,登陆失败随机延迟 0~3 秒,在返回登陆页面时附带一个随机的 user_token

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<?php

if( isset( $_GET[ 'Login' ] ) ) {
// Check Anti-CSRF token
checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );

// Sanitise username input
$user = $_GET[ 'username' ];
$user = stripslashes( $user );
$user = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $user ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));

// Sanitise password input
$pass = $_GET[ 'password' ];
$pass = stripslashes( $pass );
$pass = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $pass ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));
$pass = md5( $pass );

// Check database
$query = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";
$result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' );

if( $result && mysqli_num_rows( $result ) == 1 ) {
// Get users details
$row = mysqli_fetch_assoc( $result );
$avatar = $row["avatar"];

// Login successful
echo "<p>Welcome to the password protected area {$user}</p>";
echo "<img src=\"{$avatar}\" />";
}
else {
// Login failed
sleep( rand( 0, 3 ) );
echo "<pre><br />Username and/or password incorrect.</pre>";
}

((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);
}

// Generate Anti-CSRF token
generateSessionToken();

?>

漏洞利用

浏览器中查看网页源码,url 中是上一次登录时提交的 user_token ,源码中隐藏着本次登录需要提交的 user_token

同样使用 Burp Suite,先将请求数据发送给 Intruder 模块,用 § 符号标记需要测试的两个数据,一个是 password,另一个是 user_token,本次使用 Pitchfork 攻击方式。

在 Option 选项中找到 Grep - Extract,设置从响应中获取 user_token ,这里用光标选中想要的内容即可。

第一个数据 password 仍然使用 Kali 内置的爆破字典 /usr/share/wordlists/fasttrack.txt

第二个数据 user_token 从响应页面中递归获取,起始数据为当前未提交登录的页面的 user_token

最后一列数据表示从响应页面中提取的 user_token,同样暴力破解成功。

参阅

Impossioble

源码解析

登陆失败随机延迟 2~4 秒,登陆失败 3 次锁定 15 分钟;使用预处理的 SQL 语句,先创建 SQL 语句模板发送给数据库,数据库进行解析、编译,再向数据库发送查询的参数,数据库对参数不进行解析,因此可以用于防御 SQL 注入攻击。

预处理使用 PHP 数据对象(PHP Data Object, PDO)扩展实现。

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<?php

if( isset( $_POST[ 'Login' ] ) && isset ($_POST['username']) && isset ($_POST['password']) ) {
// Check Anti-CSRF token
checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );

// Sanitise username input
$user = $_POST[ 'username' ];
$user = stripslashes( $user );
$user = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $user ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));

// Sanitise password input
$pass = $_POST[ 'password' ];
$pass = stripslashes( $pass );
$pass = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $pass ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));
$pass = md5( $pass );

// Default values
$total_failed_login = 3;
$lockout_time = 15;
$account_locked = false;

// Check the database (Check user information)
$data = $db->prepare( 'SELECT failed_login, last_login FROM users WHERE user = (:user) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR );
$data->execute();
$row = $data->fetch();

// Check to see if the user has been locked out.
if( ( $data->rowCount() == 1 ) && ( $row[ 'failed_login' ] >= $total_failed_login ) ) {
// User locked out. Note, using this method would allow for user enumeration!
//echo "<pre><br />This account has been locked due to too many incorrect logins.</pre>";

// Calculate when the user would be allowed to login again
$last_login = strtotime( $row[ 'last_login' ] );
$timeout = $last_login + ($lockout_time * 60);
$timenow = time();

/*
print "The last login was: " . date ("h:i:s", $last_login) . "<br />";
print "The timenow is: " . date ("h:i:s", $timenow) . "<br />";
print "The timeout is: " . date ("h:i:s", $timeout) . "<br />";
*/

// Check to see if enough time has passed, if it hasn't locked the account
if( $timenow < $timeout ) {
$account_locked = true;
// print "The account is locked<br />";
}
}

// Check the database (if username matches the password)
$data = $db->prepare( 'SELECT * FROM users WHERE user = (:user) AND password = (:password) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR);
$data->bindParam( ':password', $pass, PDO::PARAM_STR );
$data->execute();
$row = $data->fetch();

// If its a valid login...
if( ( $data->rowCount() == 1 ) && ( $account_locked == false ) ) {
// Get users details
$avatar = $row[ 'avatar' ];
$failed_login = $row[ 'failed_login' ];
$last_login = $row[ 'last_login' ];

// Login successful
echo "<p>Welcome to the password protected area <em>{$user}</em></p>";
echo "<img src=\"{$avatar}\" />";

// Had the account been locked out since last login?
if( $failed_login >= $total_failed_login ) {
echo "<p><em>Warning</em>: Someone might of been brute forcing your account.</p>";
echo "<p>Number of login attempts: <em>{$failed_login}</em>.<br />Last login attempt was at: <em>${last_login}</em>.</p>";
}

// Reset bad login count
$data = $db->prepare( 'UPDATE users SET failed_login = "0" WHERE user = (:user) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR );
$data->execute();
} else {
// Login failed
sleep( rand( 2, 4 ) );

// Give the user some feedback
echo "<pre><br />Username and/or password incorrect.<br /><br/>Alternative, the account has been locked because of too many failed logins.<br />If this is the case, <em>please try again in {$lockout_time} minutes</em>.</pre>";

// Update bad login count
$data = $db->prepare( 'UPDATE users SET failed_login = (failed_login + 1) WHERE user = (:user) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR );
$data->execute();
}

// Set the last login time
$data = $db->prepare( 'UPDATE users SET last_login = now() WHERE user = (:user) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR );
$data->execute();
}

// Generate Anti-CSRF token
generateSessionToken();

?>

参阅